Resistance-No Resistance wire welder

[xMackx]

Bapgood, did you fill your aligator clips with solder?

 

[bapgood]

Bapgood, did you fill your aligator clips with solder?

Yeah some pieces of solid copper wire for filler and solder, the ground flush(ish).

 

[gdeal]

Going into the oddy clone tonight....

Flat Kanthal .8x.1mm with 30g silver - .9Ω

...courtesy of gsa's super welder.....

 

[LucentShadow]

I made one of these beasts out of an old 30v HP printer power supply and a bunch of parts from Radio Shack. I can't really recommend the Radio Shack parts, but I was impatient. The cost was about 50 bucks with some parts left over, and they have no ESR specs on the caps. Here's the welder part:



I decided to make it adjustable voltage, and just went with what Radio Shack had in the store for a fairly simple design. It puts out from 1.5v to 28v at fairly low amperage. Here is the circuit design:



C1 - .1 uF disc capacitor to reduce ripple from the long output cord on the power supply
C2 & C3 - 2200 uF 50v electrolytic capacitors, soldered between the two outputs, inside the box
R1 - two 470Ω 1/4W resistors in parallel
R2 - 5kΩ linear-taper 1/2W potentiometer
R3 - four 470Ω 1/2W resistors in series-parallel as current limiter

The LM317T was attached to a folded piece (about 2/3) of the optional metal cover from the project box with some homemade thermally-conductive epoxy as a heatsink, and stuck to the bottom of the box, since the LM317T ties the output pin to the heatsink attachment, for some reason. Everything else was attached to the cover and hacked together directly with solder, wires, and even wire nuts. The build quality sucks, but it should be sound. Again, I was impatient...

I probably went overboard on the current limiting, but I didn't want to mess with anything burning out. It charges to around 95% of full charge in 4 seconds or so, which is fine by me.



I haven't had much time to figure out how to get it to work well, yet. My initial attempts tended to either blow the wires away from each other, or ended up with little to no weld strength. I quickly figured out that I needed to keep the resistance wire much shorter than I was, from the end of the clip. I also added a 1000 uF optional capacitor (shown above) attached to a banana plug. I'll have to be careful to attach it in the correct polarity when and if I use it.

I think I'm going to try to figure out some way to spot weld the wires in place, when I get a chance to play with this some more. Or, maybe make a lever-action jig to sort of stamp them together in good alignment. I noticed that I got some very minor flash burn from the dozen or so sparks that I had to look at while trying to touch the wires together correctly. I'm not too keen on that. At a minimum, I'll probably cut a very narrow slot into some wood, and try to weld them in there.

Anyway, thanks for a great thread! I'll certainly report anything that I may find to make this better.

 

[mre777]

I like the way you added the cap with the banana plug. Could be a useful method of dialing in the capacitance.

 

[LucentShadow]

I like the way you added the cap with the banana plug. Could be a useful method of dialing in the capacitance.

I should add that I'll end up clearly marking the polarity and insulating it to reduce the shock hazard. It was my intention to possibly use this with higher capacitance for other purposes later, though.

Some sort of plug that can't be reversed would probably be a better idea.

 

[bapgood]

I should add that I'll end up clearly marking the polarity and insulating it to reduce the shock hazard. It was my intention to possibly use this with higher capacitance for other purposes later, though.

Some sort of plug that can't be reversed would probably be a better idea.

My welder has changed a little bit but high current polarized RC connectors work good and are relatively cheap. I used Dean's as I had them and don't use that type anymore, there are a ton of varieties out there.

 

[breaktru]

My welder has changed a little bit but high current polarized RC connectors work good and are relatively cheap. I used Dean's as I had them and don't use that type anymore, there are a ton of varieties out there.

You forgot to include the Scubatdan "Electrically Hot Wrapped coil winder".

 

[TBinAZ]

You forgot to include the Scubatdan "Electrically Hot Wrapped coil winder".

Now you done did it... I sense a new and improved bapgood all-in-one coming soon.

 

[xMackx]

Going into the oddy clone tonight....

Flat Kanthal .8x.1mm with 30g silver - .9Ω

...courtesy of gsa's super welder.....

I'm very interested in how the flat kanthal performs. I may just take some kanthal to my anvil and see for myself.

 

[bapgood]

You forgot to include the Scubatdan "Electrically Hot Wrapped coil winder".

Yeah yeah yeah ....This pre-dates the Scubatdan "Electrically Hot Wrapped coil winder"

I'm using higher voltage input then most of you, and higher than is wanted for EHW.....But I have some LM2596's.....So maybe it's time for the rba mega station.

- 3 Station break in/test atty connectors
- Welder
- Electrically Hot Wrapped coil winder
- Plus whatever I'm missing

 

[TBinAZ]

Yeah yeah yeah ....This pre-dates the Scubatdan "Electrically Hot Wrapped coil winder"

I'm using higher voltage input then most of you, and higher than is wanted for EHW.....But I have some LM2596's.....So maybe it's time for the RBA mega station.

- 3 Station break in/test atty connectors
- Welder
- Electrically Hot Wrapped coil winder
- Plus whatever I'm missing

See?? I told ya, breaktru.

Can't wait. LOL

 

[bapgood]

See?? I told ya, breaktru.

Can't wait. LOL

Gota use the 150 watt step up board somewhere

I know a lot of peeps are harvesting good wire from larger gauge stranded wire....But I found this 100' 28g Nickel ($8) to try....since all my welds break on the 32g nickel wire just after the weld.

 

[bapgood]

The 28g nickel to 28g kanthal is awesome!

I was easily able to do a straight up .... weld....could hardly see where the weld was (lost my fancy lens or you better believe I would be showing that bad boy off).

My weld test process is to do a pull test and then a wrap test, tightly pulling wrapping one direction and then unwrapping into a wrap the other direction.

Until now everything I have welded has failed at the unwrap/rewrap point once I have the settings dialed in for the wires I'm using. They still work, but couldn't be manhandled and rewrapped. The nickel would always break just away from the weld, usually around an 1/8" or so.

But the 28/28 .... weld held for 3 hard wrap/rewrap cycles and finally broke when I tried to bend it at the weld.

I'm not sure about 28g nickel to 32g kanthal though...I need to work on the settings some more...so its tbd

30g nickel would probably be a good all around

 

[TomCatt]

I haven't been following this thread lately . So sorry if something like this has been covered already.

I had ordered some LM2577 modules from eBay and recently got them in. I put together a welder, but when I charge up the capacitors they drain quickly. I actually have to quickly press and release the momentary switch to get the capacitors up to the set voltage and then hold the switch down to maintain the voltage. If I just press the switch and hold it, the voltage never reaches the set voltage. Here's a drawing of my setup, anyone have any ideas on what's going on?

 

[bapgood]

I haven't been following this thread lately . So sorry if something like this has been covered already.

I had ordered some LM2577 modules from eBay and recently got them in. I put together a welder, but when I charge up the capacitors they drain quickly. I actually have to quickly press and release the momentary switch to get the capacitors up to the set voltage and then hold the switch down to maintain the voltage. If I just press the switch and hold it, the voltage never reaches the set voltage. Here's a drawing of my setup, anyone have any ideas on what's going on?

The volt meter drains the capacitor charge when you use it to display the voltage on the capacitors. I think most people using the LM's are using a meter on the LM output.

 

[TomCatt]

I just clipped the yellow wire and tested with a multimeter. Still had to push the switch multiple times to bring voltage up to LM2577 set point. Once voltage was at set point, I checked the voltage periodically (~every 5-10 seconds) by momentarily touching the multimeter leads to the clips and then removing them. Same thing is happening, the capacitors are not holding voltage.

Things that make you go hmmmm ...

 

[TomCatt]

This is the same multimeter I used to check voltage on my disposable camera welder and had no problems with it there.



btw, thanks for the reply bap

 

[bapgood]

This is the same multimeter I used to check voltage on my disposable camera welder and had no problems with it there.



btw, thanks for the reply bap

Try the momentary switch between the output and caps...If that works then you will just have to add an on/off switch between the battery and LM.

If that doesn't work then I'm lost.

I have mine setup with dpdt radio shack rocker on the LM output. I use one side on the switch for charging the caps and the other to toggle the display between the LM output when the switch is off and the cap charge voltage when the switch is on.

 

[dsy5]

when I charge up the capacitors they drain quickly. I actually have to quickly press and release the momentary switch to get the capacitors up to the set voltage and then hold the switch down to maintain the voltage. If I just press the switch and hold it, the voltage never reaches the set voltage.

Try the momentary switch between the output and caps...If that works then you will just have to add an on/off switch between the battery and LM.

Do as bap suggested; this is my preferred setup since there is will be no drain by the LM board. The caps will bleed off by themselves a bit on their own, but the voltmeter will drain them, as well as the board, much faster.